This first M1-based iMac is based on the smaller 21.5" Intel iMac, and that one didn't have the user-openable RAM door on it, hasn't for quite some time, so I seriously doubt that the new 24" M1 one does, either. Aside from that, as has been mentioned, due to the whole M1 chip configuration (everything integrated right on it) this makes it unlikely to even have a user-accessible RAM door on the upcoming larger-display replacement for the 27" intel version. I think the days of users being able to tinker with their innards of their Macs have now sailed into the sunset..... Possibly it will still be possible, though, on the next version of the Mac Pro?
I'm sitting out this round of new releases, am patiently waiting for the arrival of the M2-based 16" MBP with all the trimmings..... Decided that my current iPad Pro and iPad Mini 5 are doing just fine and don't need replacing, and am not interested in the Air Tags or other stuff being offered this time around. I will be interested in hearing about how well the Air Tags actually do work in actual everyday use, though.